A mobile terminal apparatus includes a casing 8, an operation key member 10 disposed on one external face 9a of the casing 8, a circuit board 11 disposed inside the casing 8 so as to face the operation key member 10, and a battery 12 disposed inside the casing 8 so as to face the circuit board 11 on a side opposite the operation key member 10. The battery 12 includes board supporting parts 15 for supporting the circuit board 11, the board supporting parts 15 having tip portions 15a abutting against the circuit board 11 at positions facing the circuit board 11.